FCoE (fiber channel over Ethernet) is a technique for network convergence which utilizes fiber channel packets to enable an FC SAN (storage area network) and an Ethernet LAN (local area network) to share a single integrated network infrastructure, thus solves problems stemming from co-existence of networks of different types.
In an FCoE/TRILL (transparent interconnection of lots of links) convergence network, switches on the access layer (also referred to as access switches) and switches on the convergence layer (also referred to as convergence switches) both serve as Rbridges (routing bridges) in the TRILL network. Access switches are equipped with FCoE functions, and convergence switches are not equipped with FCoE functions.
Access switches have FCoE forwarding capabilities and TRILL forwarding capabilities, but do not support performing TRILL forwarding on packets which have been through FCoE forwarding nor performing FCoE forwarding on packets which have been through TRILL termination processing. Conventional access switches generally adopt port loopback for forwarding FCoE packets in a TRILL network, i.e., FCoE packets can be forwarded in a TRILL network only through loopback ports of switches on the access layer. Loopback ports occupy port resources. Furthermore, performances of the loopback ports may become the factor that restricts the performances of FCoE forwarding.